scholarly journals Autosomal dominant VCP hypomorph mutation impairs disaggregation of PHF-tau

Science ◽  
2020 ◽  
Vol 370 (6519) ◽  
pp. eaay8826 ◽  
Author(s):  
Nabil F. Darwich ◽  
Jessica M. Phan ◽  
Boram Kim ◽  
EunRan Suh ◽  
John D. Papatriantafyllou ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Neurofibrillary Tangles ◽  
Therapeutic Target ◽  
Autosomal Dominant ◽  
Genetic Mutation ◽  
Neurofibrillary Degeneration ◽  
Wild Type ◽  
Intracerebral Microinjection

Neurodegeneration in Alzheimer’s disease (AD) is closely associated with the accumulation of pathologic tau aggregates in the form of neurofibrillary tangles. We found that a p.Asp395Gly mutation in VCP (valosin-containing protein) was associated with dementia characterized neuropathologically by neuronal vacuoles and neurofibrillary tangles. Moreover, VCP appeared to exhibit tau disaggregase activity in vitro, which was impaired by the p.Asp395Gly mutation. Additionally, intracerebral microinjection of pathologic tau led to increased tau aggregates in mice in which p.Asp395Gly VCP mice was knocked in, as compared with injected wild-type mice. These findings suggest that p.Asp395Gly VCP is an autosomal-dominant genetic mutation associated with neurofibrillary degeneration in part owing to reduced tau disaggregation, raising the possibility that VCP may represent a therapeutic target for the treatment of AD.

scholarly journals Flow-cytometric microglial sorting coupled with quantitative proteomics identifies moesin as a highly-abundant microglial protein with relevance to Alzheimer’s disease

2019 ◽  
Author(s):  
Sruti Rayaprolu ◽  
Tianwen Gao ◽  
Hailian Xiao ◽  
Supriya Ramesha ◽  
Laura D. Weinstock ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Cell Sorting ◽  
Ribosomal Proteins ◽  
Molecular Mechanisms ◽  
Synaptic Proteins ◽  
Wild Type ◽  
Proteomic Data ◽  
Core Set

AbstractBackgroundProteomic characterization of microglia provides the most proximate assessment of functionally relevant molecular mechanisms of neuroinflammation. However, microglial proteomics studies have been limited by low cellular yield and contamination by non-microglial proteins using existing enrichment strategies.MethodsWe coupled magnetic-activated cell sorting (MACS) and fluorescence activated cell sorting (FACS) of microglia with tandem mass tag-mass spectrometry (TMT-MS) to obtain a highly-pure microglial proteome and identified a core set of highly-abundant microglial proteins in adult mouse brain. We interrogated existing human proteomic data for Alzheimer’s disease (AD) relevance of highly-abundant microglial proteins and performed immuno-histochemical and in-vitro validation studies.ResultsQuantitative multiplexed proteomics by TMT-MS of CD11b+ MACS-enriched (N = 5 mice) and FACS-isolated (N = 5 mice), from adult wild-type mice, identified 1,791 proteins. A total of 203 proteins were highly abundant in both datasets, representing a core-set of highly abundant microglial proteins. In addition, we found 953 differentially enriched proteins comparing MACS and FACS-based approaches, indicating significant differences between both strategies. The FACS-isolated microglia proteome was enriched with cytosolic, endoplasmic reticulum, and ribosomal proteins involved in protein metabolism and immune system functions, as well as an abundance of canonical microglial proteins. Conversely, the MACS-enriched microglia proteome was enriched with mitochondrial and synaptic proteins and higher abundance of neuronal, oligodendrocytic and astrocytic proteins. From the 203 consensus microglial proteins with high abundance in both datasets, we confirmed microglial expression of moesin (Msn) in wild-type and 5xFAD mouse brains as well as in human AD brains. Msn expression is nearly exclusively found in microglia that surround Aβ plaques in 5xFAD brains. In in-vitro primary microglial studies, Msn silencing by siRNA decreased Aβ phagocytosis and increased lipopolysaccharide-induced production of the pro-inflammatory cytokine, tumor necrosis factor (TNF). In network analysis of human brain proteomic data, Msn was a hub protein of an inflammatory co-expression module positively associated with AD neuropathological features and cognitive dysfunction.ConclusionsUsing FACS coupled with TMT-MS as the method of choice for microglial proteomics, we define a core set of highly-abundant adult microglial proteins. Among these, we validate Msn as highly-abundant in plaque-associated microglia with relevance to human AD.

scholarly journals Plasma Aβ ratios in autosomal dominant Alzheimer’s disease: the influence of genotype

2021 ◽  
Author(s):  
Antoinette O’Connor ◽  
Josef Pannee ◽  
Teresa Poole ◽  
Charles Arber ◽  
Erik Portelius ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Autosomal Dominant ◽  
Age At Onset ◽  
Cross Sectional ◽  
Autosomal Dominant Alzheimer’S Disease ◽  
Liquid Chromatography Tandem Mass ◽  
The Relationship

AbstractIn-vitro studies of autosomal dominant Alzheimer’s disease (ADAD) implicate longer Aβ peptides in pathogenesis, however less is known about the behaviour of ADAD mutations in-vivo. In this cross-sectional cohort study, we used liquid chromatography-tandem mass spectrometry to analyse 66 plasma samples from ADAD family members who were at-risk of inheriting a mutation or were already symptomatic. We tested for differences in plasma Aβ42:38, 38:40 and 42:40 ratios between Presenilin1 (PSEN1) and Amyloid Precursor Protein (APP) carriers. We examined the relationship between plasma and in-vitro models of Aβ processing and, among PSEN1 carriers, tested for associations with parental age at onset (AAO). 39 participants were mutation carriers (28 PSEN1 and 11 APP). Age- and sex-adjusted models showed marked differences in plasma Aβ between APP and PSEN1: higher Aβ42:38 in PSEN1 versus APP (p<0.001) and non-carriers (p<0.001); higher Aβ38:40 in APP versus PSEN1 (p<0.001) and non-carriers (p<0.001), while Aβ42:40 was higher in APP and PSEN1 compared to non-carriers (both p<0.001). Aβ profiles were reasonably consistent in plasma and cell lines. Within PSEN1, sex-adjusted models demonstrated negative associations between (i)Aβ42:40 (ii)Aβ42:38 and parental AAO. In-vivo differences in Aβ processing between APP and PSEN1 provide insights into ADAD pathophysiology which can inform therapy development.

scholarly journals Extensive Anti-CoA Immunostaining in Alzheimer’s Disease and Covalent Modification of Tau by a Key Cellular Metabolite Coenzyme A

2021 ◽  
Vol 15 ◽  
Author(s):  
Tammaryn Lashley ◽  
Maria-Armineh Tossounian ◽  
Neve Costello Heaven ◽  
Samantha Wallworth ◽  
Sew Peak-Chew ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Neurofibrillary Tangles ◽  
Cellular Response ◽  
Protein Modification ◽  
Coenzyme A ◽  
Neurodegenerative Disorder ◽  
Regulation Of Gene Expression ◽  
Covalent Modification

Alzheimer’s disease (AD) is a neurodegenerative disorder, accounting for at least two-thirds of dementia cases. A combination of genetic, epigenetic and environmental triggers is widely accepted to be responsible for the onset and development of AD. Accumulating evidence shows that oxidative stress and dysregulation of energy metabolism play an important role in AD pathogenesis, leading to neuronal dysfunction and death. Redox-induced protein modifications have been reported in the brain of AD patients, indicating excessive oxidative damage. Coenzyme A (CoA) is essential for diverse metabolic pathways, regulation of gene expression and biosynthesis of neurotransmitters. Dysregulation of CoA biosynthesis in animal models and inborn mutations in human genes involved in the CoA biosynthetic pathway have been associated with neurodegeneration. Recent studies have uncovered the antioxidant function of CoA, involving covalent protein modification by this cofactor (CoAlation) in cellular response to oxidative or metabolic stress. Protein CoAlation has been shown to both modulate the activity of modified proteins and protect cysteine residues from irreversible overoxidation. In this study, immunohistochemistry analysis with highly specific anti-CoA monoclonal antibody was used to reveal protein CoAlation across numerous neurodegenerative diseases, which appeared particularly frequent in AD. Furthermore, protein CoAlation consistently co-localized with tau-positive neurofibrillary tangles, underpinning one of the key pathological hallmarks of AD. Double immunihistochemical staining with tau and CoA antibodies in AD brain tissue revealed co-localization of the two immunoreactive signals. Further, recombinant 2N3R and 2N4R tau isoforms were found to be CoAlated in vitro and the site of CoAlation mapped by mass spectrometry to conserved cysteine 322, located in the microtubule binding region. We also report the reversible H2O2-induced dimerization of recombinant 2N3R, which is inhibited by CoAlation. Moreover, CoAlation of transiently expressed 2N4R tau was observed in diamide-treated HEK293/Pank1β cells. Taken together, this study demonstrates for the first time extensive anti-CoA immunoreactivity in AD brain samples, which occurs in structures resembling neurofibrillary tangles and neuropil threads. Covalent modification of recombinant tau at cysteine 322 suggests that CoAlation may play an important role in protecting redox-sensitive tau cysteine from irreversible overoxidation and may modulate its acetyltransferase activity and functional interactions.

scholarly journals In vitro studies of amyloid β-protein fibril assembly and toxicity provide clues to the aetiology of Flemish variant (Ala692→Gly) Alzheimer's disease

2001 ◽  
Vol 355 (3) ◽  
pp. 869-877 ◽  
Author(s):  
Dominic M. WALSH ◽  
Dean M. HARTLEY ◽  
Margaret M. CONDRON ◽  
Dennis J. SELKOE ◽  
David B. TEPLOW
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Amino Acid ◽  
Amino Acid Substitution ◽  
Amyloid Β ◽  
In Vitro Studies ◽  
Amyloid Β Protein ◽  
Wild Type ◽  
Β Protein

In a Flemish kindred, an Ala692 → Gly amino acid substitution in the amyloid β-protein precursor (AβPP) causes a form of early-onset Alzheimer's disease (AD) which displays prominent amyloid angiopathy and unusually large senile plaque cores. The mechanistic basis of this Flemish form of AD is unknown. Previous in vitro studies of amyloid β-protein (Aβ) production in HEK-293 cells transfected with cDNA encoding Flemish AβPP have shown that full-length [Aβ(1–40)] and truncated [Aβ(5–40) and Aβ(11–40)] forms of Aβ are produced. In an effort to determine how these peptides might contribute to the pathogenesis of the Flemish disease, comparative biophysical and neurotoxicity studies were performed on wild-type and Flemish Aβ(1–40), Aβ(5–40) and Aβ(11–40). The results revealed that the Flemish amino acid substitution increased the solubility of each form of peptide, decreased the rate of formation of thioflavin-T-positive assemblies, and increased the SDS-stability of peptide oligomers. Although the kinetics of peptide assembly were altered by the Ala21 → Gly substitution, all three Flemish variants formed fibrils, as did the wild-type peptides. Importantly, toxicity studies using cultured primary rat cortical cells showed that the Flemish assemblies were as potent a neurotoxin as were the wild-type assemblies. Our results are consistent with a pathogenetic process in which conformational changes in Aβ induced by the Ala21 → Gly substitution would facilitate peptide adherence to the vascular endothelium, creating nidi for amyloid growth. Increased peptide solubility and assembly stability would favour formation of larger deposits and inhibit their elimination. In addition, increased concentrations of neurotoxic assemblies would accelerate neuronal injury and death.

scholarly journals Reactive astrocytes augment hippocampal inhibitory tone via GABA transporter-3/4 to facilitate synaptic balance in Alzheimer’s disease

2021 ◽  
Author(s):  
Yousif Aldabbagh ◽  
Anam Islam ◽  
Weicong Zhang ◽  
Paul Whiting ◽  
Afia Ali
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Tonic Inhibition ◽  
Reactive Astrocytes ◽  
Post Mortem ◽  
Wild Type ◽  
Gaba Transporter ◽  
Synaptic Excitation ◽  
Post Mortem Brain

Background and Purpose: Cognitive decline is a major symptom in Alzheimer’s disease (AD), which is closely associated with synaptic excitatory-inhibitory imbalance. Here, we investigated whether astrocytic mechanisms involving the astrocyte-specific GABA transporter 3/4 (GAT3/4) play a role in altering the synaptic balance in AD and whether these mechanisms correlate with presynaptic cannabinoid type-1 receptors (CB1-Rs). Experimental approach: Using the APPNL-F/NL-F knock-in mouse model of AD, aged-matched to wild-type mice, we performed in vitro electrophysiological whole-cell recordings combined with immunohistochemistry in the CA1 and dentate gyrus (DG) regions of the hippocampus. Comparative neuroanatomy experiments were also performed in post-mortem brain tissue from human AD patients, age-matched to healthy controls. Results: We observed a higher expression of GABA content and GAT3/4 co-localised with reactive astrocytes, which enhanced tonic inhibition in the CA1, and DG of APPNL-F/NL-F mice compared to the age-matched wild-type animals. Blocking GAT3/4 - associated tonic inhibition in APPNL-F/NL-F mice resulted in an enhanced frequency of synaptic excitation, suggesting a presynaptic mechanism. These data also correlated with an up-regulation of CB1-Rs in astrocytes and cholecystokinin (CCK)-containing interneurons, which also enhanced tonic inhibition in the AD model, but did not affect GAT3/4 -associated tonic inhibition. The neuroanatomical results were mirrored in post-mortem tissue of AD patients. Conclusions: Our data suggest that reactive astrocytes lead to augmented tonic inhibition in the hippocampus, which probably plays an important presynaptic compensatory role in attempting to restore AD-associated neuronal hyperactivity. Therefore, reducing tonic inhibition through GAT3/4 may not be a good therapeutic strategy for AD.

scholarly journals Generation of a humanized Aβ expressing mouse demonstrating aspects of Alzheimer’s disease-like pathology

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
David Baglietto-Vargas ◽  
Stefania Forner ◽  
Lena Cai ◽  
Alessandra C. Martini ◽  
Laura Trujillo-Estrada ◽  
...  
Keyword(s):  
Gene Expression ◽  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Autosomal Dominant ◽  
Late Onset ◽  
Periodic Acid ◽  
Wild Type ◽  
Periodic Acid Schiff ◽  
Human Counterpart ◽  
Age Dependent

AbstractThe majority of Alzheimer’s disease (AD) cases are late-onset and occur sporadically, however most mouse models of the disease harbor pathogenic mutations, rendering them better representations of familial autosomal-dominant forms of the disease. Here, we generated knock-in mice that express wildtype human Aβ under control of the mouse App locus. Remarkably, changing 3 amino acids in the mouse Aβ sequence to its wild-type human counterpart leads to age-dependent impairments in cognition and synaptic plasticity, brain volumetric changes, inflammatory alterations, the appearance of Periodic Acid-Schiff (PAS) granules and changes in gene expression. In addition, when exon 14 encoding the Aβ sequence was flanked by loxP sites we show that Cre-mediated excision of exon 14 ablates hAβ expression, rescues cognition and reduces the formation of PAS granules.

scholarly journals A TauP301L mouse model of dementia; development of pathology, synaptic transmission, microglial response and cognition throughout life

2018 ◽  
Author(s):  
Zelah Joel ◽  
Pablo Izquierdo ◽  
Wenfei Liu ◽  
Chloe Hall ◽  
Martha Roberts ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Synaptic Transmission ◽  
Neurofibrillary Tangles ◽  
Late Stage ◽  
Tau Hyperphosphorylation ◽  
Protein Levels ◽  
Field Recordings ◽  
Plaque Load

AbstractBackgroundLate stage Alzheimer’s disease and other dementias are associated with neurofibrillary tangles and neurodegeneration. Here we describe a mouse (TauD35) carrying human Tau with the P301L mutation that results in Tau hyperphosphorylation and tangles. Previously we have compared gene expression in TauD35 mice to mice which develop plaques but no tangles. A similar comparison of other pathological features throughout disease progression is made here between amyloidβ and Tau mice described in Parts I and II of this study.MethodsIn vitro CA1 patch clamp and field recordings were used to investigate synaptic transmission and plasticity. Plaque load and microglia were investigated with immunohistochemistry. Cognition, locomotor activity and anxiety-related behaviours were assessed with a forced-alternation T-maze, open field and light/dark box.ResultsTransgene copy number in TauD35 mice fell into two groups (HighTAU and LowTAU), allowing assessment of dose-dependent effects of overexpression and resulting in tangle load increasing 100-fold for a 2-fold change in protein levels. Tangles were first detected at 8 (HighTAU) or 13 months (LowTAU) but the effects on synaptic transmission and plasticity and behaviour were subtle. However, severe neurodegeneration occurred in HighTAU mice at around 17 months, preceded by considerable proliferation and activation of microglia at 13 months of age; both increasing further at 17 months. LowTAU mice at 24 months of age showed a comparable tangle load and microglial proliferation to that occurring at 13 months in HighTAU mice. However, LowTAU mice showed no neurodegeneration at this stage and considerable microglial activation, stressing the dependence of these effects on overexpression and/or age.ConclusionsComparison of the effects of amyloidβ and plaques without tangles in a model of preclinical Alzheimer’s disease to the effects of tangles without amyloidβ plaques in the late stage model described here may clarify the progressive stages of Alzheimer’s disease. While Tau hyperphosphorylation and neurofibrillary tangles are eventually sufficient to cause severe neurodegeneration, initial effects on synaptic transmission and the immune response are subtle. In contrast while even with a heavy plaque load little if any neurodegeneration occurs, considerable effects on synaptic transmission and the immune system result, even before plaques are detectable.

scholarly journals Dephosphorylation Passivates the Seeding Activity of Oligomeric Tau Derived From Alzheimer’s Brain

2021 ◽  
Vol 14 ◽  
Author(s):  
Ruozhen Wu ◽  
Longfei Li ◽  
Ruirui Shi ◽  
Yan Zhou ◽  
Nana Jin ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Neurofibrillary Tangles ◽  
Cultured Cells ◽  
Phosphorylated Tau ◽  
Western Blots ◽  
Tau Aggregation

Accumulation of intracellular neurofibrillary tangles (NFTs), which are constituted of abnormally phosphorylated tau, is one of the neuropathological hallmarks of Alzheimer’s disease (AD). The oligomeric aggregates of tau in AD brain (AD O-tau) are believed to trigger NFT spreading by seeding normal tau aggregation as toxic seeds, in a prion-like fashion. Here, we revealed the features of AD O-tau by Western blots using antibodies against various epitopes and determined the effect of dephosphorylation on the seeding activity of AD O-tau by capture and seeded aggregation assays. We found that N-terminal truncated and C-terminalhyperphosphorylated tau species were enriched in AD O-tau. Dephosphorylation of AD O-tau by alkaline phosphatasediminished its activity in capturing tau in vitro and ininducing insoluble aggregates in cultured cells. Our resultssuggested that dephosphorylation passivated the seeding activity ofAD O-tau. Inhibition of phosphorylation may be a potentstrategy to prevent the spreading of tau patho3logy.

scholarly journals Switched Aβ43 generation in familial Alzheimer’s disease with presenilin 1 mutation

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Nobuto Kakuda ◽  
Mako Takami ◽  
Masayasu Okochi ◽  
Kensaku Kasuga ◽  
Yasuo Ihara ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Middle Ages ◽  
Senile Plaques ◽  
Genetic Mutation ◽  
Familial Alzheimer’S Disease ◽  
Cerebral Parenchyma ◽  
Familial Alzheimer's Disease ◽  
Aβ Generation

AbstractPresenilin (PS) with a genetic mutation generates abundant β-amyloid protein (Aβ) 43. Senile plaques are formed by Aβ43 in the cerebral parenchyma together with Aβ42 at middle ages. These brains cause the early onset of Alzheimer’s disease (AD), which is known as familial Alzheimer’s disease (FAD). Based on the stepwise processing model of Aβ generation by γ-secretase, we reassessed the levels of Aβs in the cerebrospinal fluid (CSF) of FAD participants. While low levels of Aβ38, Aβ40, and Aβ42 were generated in the CSF of FAD participants, the levels of Aβ43 were unchanged in some of them compared with other participants. We sought to investigate why the level of Aβ43 was unchanged in FAD participants. These characteristics of Aβ generation were observed in the γ-secretase assay in vitro using cells, which express FAD mutations in PS1. Aβ38 and Aβ40 generation from their precursors, Aβ42 and Aβ43, was decreased in PS1 mutants compared with wild-type (WT) PS1, as observed in the CSF. Both the ratios of Aβ38/Aβ42 and Aβ40/Aβ43 in PS1 mutants were lower than those in the WT. However, the ratio of Aβ43/amyloid precursor protein intracellular domain (AICD) increased in the PS1 mutants in an onset age dependency, while other Aβ/AICD ratios were decreased or unchanged. Importantly, liquid chromatography–mass spectrometry found that the generation of Aβ43 was stimulated from Aβ48 in PS1 mutants. This result indicates that PS1 mutants switched the Aβ43 generating line, which reflects the level of Aβ43 in the CSF and forming senile plaques.

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